AN AMICRONUCLEATE OXYTRICHA. II 



145 



A twin culture (S5T) of four lines was begun on January 10th, 

 using the four twins in the second generation as ancestors for the 

 four lines. On January r2th a subculture of single animals 

 (S5TS) was begun from the single individuals given off from twins 

 in the third generation. On January 19th, from a stock slide 



I I 



L.... 



Fig. 9 Comparison of twin culture (S5T, continuous line) and subculture of 

 single animals (S5S, broken line) derived from the twin culture, January 10, 

 1918, to March 16, 1918. 



Fig. 10 Comparison of cannibal subcultures (S5C, continuous line) and non- 

 cannibal subcultures (S5CN, broken line). January 20, 1918, to March 16, 1918. 



from culture S5TS of four days' standing a typical cannibal 

 and a non-cannibal animal were isolated, and the progeny of 

 these in the second generation were carried in two subcultures, 

 S5C and S5N, respectively. Curves showing the division rates 

 for these four cultures are seen in figures 9 and 10. It will be 

 noted that the division rates of the twins and the single animals 



